Implementation of frequency-modulated triangular carrier and slope PWM strategies for three-level NPC inverters

Multilevel inverters produce an output voltage with superior quality compared to the voltage obtained by two-level converters. They are controlled with pulse width modulation (PWM) methods and have a limited switching frequency due to semiconductor devices switching losses. This paper presents the implementation for multilevel converters of two generated PWM methods that were previously proposed for two level converters. The considered methods, sinusoidal carrier regulated by the slope of a trapezoidal waveform PWM (SLPWM) and frequency modulated triangular carrier PWM (HIPWM-FMTC), control the output voltage spectrum while keeping the number of commutations low for a given fundamental frequency.